This project is designed to produce a test procedure for evaluating the performance of agricultural tractor operator roll over protection systems (ROPS) that will circumvent full scale testing of all systems and tractor combinations. One component of the work will develop a mathematical and computer simulation of the tractor motion during overturn to establish conditions at impact of the ROPS with the surrounding surface. A second component will be the development of physical model test procedures for ROPS through similitude analysis. The physical models will be used to predict full scale system performance. Once the procedure for scale model testing combined with computer simulation is verified as a valid technique for evaluating ROPS safety, a procedure for subsequent ROPS will be specified that will allow model tests of ROPS performance for new designs and new operating conditions.